Means for eliminating fading



June 27, 1933. M. OSNOS 1,915,578

MEANS FOR ELIMI'NATING FADING Filed June 19, 1929 Jvpk/Zens III M d/M/INVENTOR MENDEL o snos ATTORNEY difference between about 10000 cyclesper second. In the folf atented June 27, 1933 STATES PATE MENDEL osnos,or BERLIN, GERMANY, ASSIGNOR T6 TELEFUNKEN onsE-LLscHAF'r rim DRAHTLOSETELEGRAPI-IIE M. B. 1-1.,

GERMANY OF BERLIN, GERMANY, A CORPGRATION OF MEANS FOR ELIMINATINGFADING Application filed June 19, 1929, Serial No. 372,152, and inGermany June 30, 1928.

It is known that fading actions manifest themselves often only for adefinite wavelength, but not in a slightly difierent wave.

The present invention is predicated upon the practical use of thisparticular property of the fading phenomena, with the end in View ofobviating the disturbances caused by fading actions.

For this purpose, transmission according to this invention is effectedon two or more carrier waves which differ comparatively but little fromeach other, so that, if one of the waves happens to experience fadingtrouble, the other wave or waves will be transmitted.

Two embodiments based upon the fundamental idea of the invention areshown in the drawing.

In the circuit arrangement shown in Figure 1, the two tubes I and IIconstitute the first stage of a usual amplifier cascade, and theirtuning is so chosen that the difference in their wave-length is butlittle compared with the waves themselves. This can be insured mostsuitably by the convenient selection of the grid crystals 701 and 702,respectively.

For instance, if the mean frequency is 2.5 10 cycles per second, thenthe difference of about 1250 cycles per second will suffice in themajority of cases. If, then, the frequency is raised, say, eight timesby the following stages as usual, there results a thewaves sent out oflowing stages, circuits tuned to two waves are not required, indeed, itis sufficient to tune them to the mean wave. Thus A an amplifier, istuned to the mean wave-length, M indicates any suitable modulatingsource connected to the apparatus in any well known manner and A may bean amplifier and frequency multiplier.

It is advisable to set the wave-lengths, for

instance, by variable capacities of suitable kmd, C and C connected inthe grid circuit of tubes 1 and 2.

The scheme illustrated in Figure 2 is fundamentally identical withFigure 1, except that the two tubes are here connected inphase-opposition (push-pull-fashion).

The condensers C as their labels indicate, are neutralizing condensersand prevent the reaction of one oscillator upon the other and viceversa.

I claim:

1. In a system for the reduction of fading, an electron discharge deviceoscillator, a crystal for maintaining the frequency of oscillation ofthe electron discharge device oscillator at a predetermined frequency,another electron discharge device oscillator, a

crystal for maintaining the frequency of said last mentioned oscillatorat a value slightly different from the frequency of said first mentionedoscillator, means for coupling the output circuits of the oscillatorstogether, means for amplifying the combined output of the oscillators,means for modulating the amplified energy, and means for transmittingthe resulting modulated oscillations.

2. In apparatus of the character described, an electron dischargedeviceoscillator, a crystal for maintaining the frequency of oscillationof the electron discharge device oscillator at a predeterminedfrequency, another electron discharge device oscillator, a crystal formaintaining the frequency of said last mentioned oscillator at a valueslightly different from the frequency of said first mentionedoscillator, means for coupling the output circuits of the oscillatorstogether, neu tralizing condensers connected to the output and inputcircuits of said oscillators for preventing reaction of one oscillatorupon the other, and means for utilizing the combined outputs of saidoscillators.

MENDEL OSNOS.

